Design and characterization of a cough simulator

Area of Science:

• Aerosol science
• Respiratory fluid dynamics
• Infectious disease transmission

Background:

• Expiratory droplets from coughing are primary vectors for respiratory pathogen transmission.
• Understanding droplet size distribution is key to modeling disease spread.
• Previous methods lacked the ability to accurately replicate natural cough dynamics.

Purpose of the Study:

• To design and build a transient, repeatable cough simulator.
• To generate cough-generated droplets with bimodal size distributions ('fine' and 'coarse').
• To provide a tool for studying respiratory infectious disease transmission mechanisms.

Main Methods:

• Developed a cough simulator using a pressurized gas tank, nebulizer, and ejector with solenoid valves.
• Generated droplets via mucus breaking, condensation, and high-speed atomization.
• Characterized droplet sizes using fibrous collection (coarse) and laser diffraction (fine).
• Modeled droplet trajectories and vaporization using a Lagrangian approach and computational fluid dynamics (CFD).

Main Results:

• The simulator successfully produced transient sprays with bimodal droplet size characteristics.
• Droplet size distributions were accurately represented by Rosin-Rammler (coarse) and log-normal (fine) functions.
• Hydrodynamic consequences like droplet vaporization and polydispersion were assessed via modeling.

Conclusions:

• The developed cough simulator effectively mimics natural cough droplet generation.
• This tool enables more accurate research into respiratory disease transmission.
• The findings contribute to a better understanding of aerosol dynamics in coughing events.